The present invention relates, in general, to a casein hydrolysate, and, in particular, to a method of preparing a casein hydrolysate enriched in antihypertensive peptides, to the resulting hydrolysate and to a method of preventing or treating hypertension using same.
With the recent changes in eating habits, the incidence of adult diseases, including hypertension and hyperlipemia, is on the increase. There is also a mounting interest in preventive medicine and thus there is an intense search for substances that are both safe and prophylactically effective.
Animal models of diseases such as cerebral stroke (Yamori et al, Jpn. Circ. J. 38:1095 (1974)), myocardial infarction (Yamori et al, Atherosclerosis 42:15 (1982)) and arteriosclerosis have been developed. Using such models, it has been possible to demonstrate that proper nutrition can be an effective preventative even in animals having a genetic predisposition to circulatory diseases.
Experiments involving the use of animal models, namely spontaneously hypertensive rats (SHR) (Okamoto et al, Jpn. Circ. J. 27:282 (1963)) and stroke-prone SHR (SHRSP), have shown that excess intake of sodium chloride promotes high blood pressure, while certain nutrients protect against it. For example, it has been shown that when soybean protein, lysine, taurine, potassium, calcium, magnesium, palmitoleic acid, etc. are administered before the onset of hypertension, or at an early stage after onset and onwards, a prophylactic effect is obtained (Yamori et al, New horizon in preventing cardiovascular diseases, Yamori and Strasser eds., Elsevier, Amesterdam, pp. 1, (1989)).
It has become increasingly clear that substances derived from food proteins can play a variety of physiological roles. Certain of such substances have been shown to have blood cholesterol-lowering activity and antihypertensive activity (Karaki et al, Comp. Biochem. Physiol., 96C, 367, (1990)). Some are available commercially.
Recently, it has been reported that the angiotensin converting enzyme inhibitor (ACEI), captopril, inhibits the onset of stroke in the SHRSP at a dose that is not hypotensive (Ohta et al, Genetic. Hypertens. 218:393 (1992)). However, captopril has adverse side effects, such as inducing a skin rash. Administration of other substances known to be effective for circulatory diseases, particularly cerebral stroke, are also associated with adverse side effects, including induction of blood-pressure fluctuations and the like.
Therefore, from the standpoint of preventive medicine, there is a significant demand for dietary substances that are effective in preventing or delaying the onset of high blood pressure, particularly, cerebral stroke, and that are safe and relatively inexpensive. The present invention provides a method for producing such a substance.
The present invention relates to a method of preparing a casein hydrolysate that is enriched in the peptides C6, C7 and C12. The product of the present method can be used as a dietary preventative of circulatory diseases, more specifically, high blood pressure and associated diseases. Further, the present product is relatively free of adverse side effects associated with many antihypertensive pharmaceuticals.
Objects and advantages of the present invention will be clear from the description that follows.